Jamil Walker Smith

Jamil Walker Smith (born August 20, 1982) is an American actor, director, producer and writer. His best known role is as the voice of Gerald, a fourth grader and Arnold's best friend in the Nickelodeon animated TV series ''Hey Arnold!''. He also appeared on several shows like ''Sister, Sister''; ''Girlfriends''; ''Bones''; ''The X-Files''; and ''The Bernie Mac Show''. He is an actor by trade and writes, acts and directs his own short film projects. He played Master Sergeant Ronald Greer in both seasons of ''Stargate Universe''. Provided by Wikipedia